DD1 I think the point is to have a better spawning area. This will lessen energy loss of bluegill trying to get to hardpan, etc. Also increase egg/fry survivial, thus creating more bluegill. Otherwise yes they will find a way to spawn but lets help em a bit we say.
lassig, we line an area with cinder blocks. If not the gravel tends to get pushed out of the way. The deeper edge might go two cinder blocks high. Ewest says research indicates pea gravel to half dollar size is preferred. Pictures show that as well. The gravel cost adds up so extra cost in blocks helps save investment. I like the idea of fabric as well so does nto bury in muck area.
